CCK-8 can inhibit ingestive behavior by acting on the liver

The possibility that cholecystokinin octapeptide (CCK-8) can inhibit ingestive behavior by acting on the liver was investigated. Male rats were trained to ingest an intraorally infused 1 M solution of sucrose and then injected with 10 microg CCK-8/kg. Intraperitoneal or hepatic portal vein, but not jugular vein, injection suppressed intake of the sucrose solution. Intraperitoneal injection was more potent than hepatic portal vein injection. Inhibition by hepatic portal vein injection was blocked by i.p. injection of 80 microg/kg of the CCK-A receptor antagonist L-364,718 or by hepatic vagotomy. The results support the hypothesis that CCK-8 can inhibit ingestive behavior via a hormonal action on the liver.